Thursday, April 25

Storing renewable energies, one balloon at a time

Central Sardinia is not generally considered a hotbed of innovation: arid and rural, with some of its road signs riddled with bullets made by locals practicing target shooting, the setting is reminiscent of a Clint Eastwood western. Yet in Ottana, on the industrial wasteland of a former petrochemical factory, a new technology is taking shape that could help the world slow climate change. The key element of this technology is as improbable as its remote location: carbon dioxide, the main cause of global warming.

Energy Dome, a Milan-based start-up, runs an energy storage demonstration plant that helps address the inadequacy of the local electricity market. “In Sardinia, during the day, everyone goes to the sea,” said Claudio Spadacini, general manager of Energy Dome. “They don’t use electricity, but there is a lot of it,” he added, referring to the Italian island’s abundant sunlight.

Energy Dome uses the carbon dioxide contained in a huge balloon, the “dome” in the company name, as a kind of battery. During the day, electricity from the local grid, partly generated by nearby solar cell fields, is used to compress carbon dioxide into liquid. At night, liquid carbon dioxide is expanded into gas, which drives a turbine and produces electricity that is fed back to the grid.

Solar and wind energy are fast-growing renewable sources, but they rely on nature’s intermittent schedule to produce electricity. Many researchers and policymakers say storing this energy until it’s needed, for hours or even days, is key to moving economies away from fossil fuels. “Advancement in energy storage technologies is essential to achieving a decarbonized electricity grid,” said Jennifer M. Granholm, the U.S. Secretary of Energy. in a 2022 statementwhen his department announced it would spend more than $300 million on long-duration energy storage.

Companies are developing and commercializing varied and creative ways to store renewable energy: liquefying carbon dioxide, derusting iron, heating towers filled with sand at temperatures almost high enough to melt aluminum. But predicting our future energy storage needs, after a major energy transformation, is a daunting prospect, and it is difficult to know which of these approaches, if any, will prove effective and cost-effective.

“There is a real urgency to decarbonize electricity in a much faster time frame than we have considered in the past,” said Elaine Hart, founding principal of Moment Energy Insights LLC, a clean energy consultancy. “We don’t need technologies like long-duration energy storage or hydrogen today, but we may need them on a large scale in the next 15 to 20 years. So we are in a period critical for their development.